Transcript The Cell Cycle

The
Cell Cycle
Steps in the cell cycle
 Interphase: No division occurs.
Interphase has three subdivisions:
 G1
S
 G2
Interphase
 G1: Gap one




first phase,
Growth and normal processes take place.
No division occurs
Longest phase of interphase
Interphase
 S or Synthesis phase:
 Second stage
 DNA replicates
 making another copy of chromosomes.
 At the end of this phase, the nucleus will
contain two complete sets of DNA.

Interphase
 G2: Cells prepare for division.
 Shortest stage of interphase
 Spindle fibers, centrioles, etc - are prepared
for next stage
Interphase
Mitosis
 Mitosis: the division of the cell
nucleus and its contents. Mitosis has
four main stages:




Prophase
Metaphase
Anaphase
Telophase
Parent cell
Mitosis
Cytokinesis
Daughter cells
Mitosis
 Prophase: Chromosomes become
shorter, thicker, and become visible.
 Nuclear envelope begins to disappear.
 Centrioles are moving toward poles and
spindle fibers are forming.
 Spindle fibers form between centrioles.
Prophase
Mitosis
 Metaphase: The chromosomes line up
in the mid-plane of the cell.
 Spindle fibers attach to the centromere of
the chromosome.
Mitosis
 Anaphase: Sister chromatids separate
at centromeres and move away
 One group of chromosomes are pulled by
the centrioles on the spindle fibers
Anaphase
Mitosis
 Telophase:
 Chromosomes are at the poles.
 The nuclear envelopes begin to form.
 Nucleolus reforms
 Spindle fibers disappear
 Cytokinesis and telophase take place
around the same time.
Telophase
Cytokinesis
 Cytokinesis: The process that divides
the cytoplasm.
 Animal cells - The cell membrane pinches
together
Plant Cells
 In plant cells cytokinesis occurs by
forming a cell plate to form the new
cell wall.
QuickTime™ and a
decompressor
are needed to see this picture.
Answer the following
questions
1. Is this an animal or a
plant?
2. What phase is this
slide in?
3. What helped you
determine which
phase this slide was
in?
Answer the following
4. Is this an animal or
a plant?
5. What phase is this
slide in?
6. What helped you
determine which
phase this slide was
in?
Answer the following
7. Is this an animal or
a plant?
8. What phase is this
slide in?
9. What helped you
determine which
phase this slide
was in?
Answer the following
10.Is this an animal
or a plant?
11. What phase is
this slide in?
12. What helped you
determine which
phase this slide
was in?
Answer the following
13.What phase is the
cell the arrow is
on in?
14.What phase is the
cell to the left of
that cell in?
15. Name the two
differences
between plant
mitosis and
animal mitosis.
Review
 Four main stages of the cell cycle:




G1- normal growth
Synthesis- DNA is copied
Gap 2- more growth
Mitosis- nuclear division
Together, these three
stages make up
interphase.
 Prophase- chromosomes are visible, nuclear envelope
disappears
 Metaphase- chromosomes line in up in mid-plane
 Anaphase- chromosomes move away from the mid-plane
 Telophase- Chromosomes at poles nuclear envelope forms
 Cytokinesis- divides the cytoplasm